001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 */
017package org.apache.bcel.classfile;
018
019import java.io.DataInput;
020import java.io.DataOutputStream;
021import java.io.IOException;
022
023import org.apache.bcel.Const;
024
025/**
026 * This class is derived from the abstract {@link Constant} and represents a reference to a module.
027 *
028 * <p>
029 * Note: Early access Java 9 support- currently subject to change
030 * </p>
031 *
032 * @see Constant
033 * @since 6.1
034 */
035public final class ConstantModule extends Constant implements ConstantObject {
036
037    private int nameIndex;
038
039    /**
040     * Initialize from another object.
041     *
042     * @param c Source to copy.
043     */
044    public ConstantModule(final ConstantModule c) {
045        this(c.getNameIndex());
046    }
047
048    /**
049     * Initialize instance from file data.
050     *
051     * @param file Input stream
052     * @throws IOException if an I/O error occurs.
053     */
054    ConstantModule(final DataInput file) throws IOException {
055        this(file.readUnsignedShort());
056    }
057
058    /**
059     * @param nameIndex Name index in constant pool. Should refer to a ConstantUtf8.
060     */
061    public ConstantModule(final int nameIndex) {
062        super(Const.CONSTANT_Module);
063        this.nameIndex = nameIndex;
064    }
065
066    /**
067     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
068     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
069     *
070     * @param v Visitor object
071     */
072    @Override
073    public void accept(final Visitor v) {
074        v.visitConstantModule(this);
075    }
076
077    /**
078     * Dump constant module to file stream in binary format.
079     *
080     * @param file Output file stream
081     * @throws IOException if an I/O error occurs.
082     */
083    @Override
084    public void dump(final DataOutputStream file) throws IOException {
085        file.writeByte(super.getTag());
086        file.writeShort(nameIndex);
087    }
088
089    /**
090     * @return dereferenced string
091     */
092    public String getBytes(final ConstantPool cp) {
093        return (String) getConstantValue(cp);
094    }
095
096    /**
097     * @return String object
098     */
099    @Override
100    public Object getConstantValue(final ConstantPool cp) {
101        return cp.getConstantUtf8(nameIndex).getBytes();
102    }
103
104    /**
105     * @return Name index in constant pool of module name.
106     */
107    public int getNameIndex() {
108        return nameIndex;
109    }
110
111    /**
112     * @param nameIndex the name index in the constant pool of this Constant Module
113     */
114    public void setNameIndex(final int nameIndex) {
115        this.nameIndex = nameIndex;
116    }
117
118    /**
119     * @return String representation.
120     */
121    @Override
122    public String toString() {
123        return super.toString() + "(nameIndex = " + nameIndex + ")";
124    }
125}